How to make sure that a memory card is compatible to my mac?

I want to upgrade my RAM from 4g to 8g.

my mac specs are:

I need 2 4g memory cards, and this is a specific card I saw in a store that should be working, but no one gives a guarantee it will work on mac...they say it works on laptops, but they can't guarantee its working for mac...

This is the card model: G.Skill 1x4GB DDR3 1600Mhz SODIMM

Can someone help please

Thanks!